LADSPA/LV2 Telephony Plugins

I have written a couple of LADSPA/LV2 plugins for the swh-plugins suite. These plugins implement μ-Law and A-Law compression, forms of log-amplification used to increase the signal-to-noise ratio of old analog telephone lines at the expense of fidelity.

The motivation for the plugins was to add them to a LADSPA stack with some compression and bandpass filtering to implement a "telephone voice" effect; this works pretty well.

Look on GitHub at https://github.com/BartMassey/lv2/tree/telephony for my branch of the swh-plugins LV2 tree containing the extra plugins. I have a pull request in at the main swh-plugins GitHub currently.